Method of making precipitated barium sulphate



tegrated. However, the character of the ire-- Patented dune 5 M923@ 'entran sraras @FFHQa f B. EMERCE, JR., 03F CHARLESTQN, WEST VEEGIENEA l it@ Drawing,

To all 'wh'om'z't may concern.

Be it known that l, Jarras B, Pinnen, dr., a citizen of the United States, and a resident et Charleston, in the county oi Kanawha and State oi l/lf est Virginia, have invented new and use-ful lm rovements in Methods ora Making Precipitated Barium Sulphate, of which the ollowin is a specification.

rlhs invention re atesA to the production of barium sulphate, or blanc xe, and has for its principal objects the economical production of blanc fixe of an extreme degree of iineness and possessing a freedom from tot eign substances, especially alkaline, acid and neutral salts and iron, which imparts tothe resulting product the more desirable qualities irrespective of whether the ultimate particles are amorphous or crystalline.

lit is well known that precipitated barium sulphate can be prepared by double decomposition between solutions ,of barium sulphide and sodium sulphate, the sodium sulphide solution so obtained being usually decanted, and then the 'residual precipitate oit barium sulphate can be washed by decantation, dried and disinsulting product, particularly in the respects above noted, will vary considerably accord-- ing to the conditions maintained throughout the precipitation and washing periods as hereinafter explained.

l/ily investigations have led to the discovery that in the production ol precipitated barium sulphate, or blanc une, by the interaction oi barium sulphide and sodium sulphate, a liner and jmore readily lixiviated precipitateoi2 barium sulphate is obtained it a substantial maintained inl the solution throughout the i precipitation. lllloreoven that the tempera ture and employed have a` very important intluence upon the degree ot tineness and other physical characteristics oil/the precipitate. Furthermore, even the temperature and Ipurity 'et the wash water has an important intluenoe upon the fineness, color and purity ol the precipitated barium sulphate produced.

lin carrying mit my invention l preferably proceed as follows: ,y

- A solution ci, barium sulphide is caused to interact with a solution el sodium sulphate, the barium sulphide being maintained in excess, throughout the precipitatiomb that theoreticallyl required to satisfy the sodium excess of barium sulphide is.

strength oiuthe reacting ,solutions y Application nled october t, 3321i. Serial No. 50u38?. i

sulphate. 'lhe temperatures ot the solution or barium l sulphide and sodium sulphate are maintained at such points that the tempera ture of the mixturein the precipitating ves= sel will range between C. and 100 (Il,

preferably from 00 (C. to 75 G., throughout the precipitation, Between these vtemperaI tures the precipitated barium sulphate is liner than it the solution were colderv and furthermore the precipitated barium sulphatedue to the tineness and physical characteristics thereof, tends to settle much faster in the precipitating vessel, with a consequence that the top liquor and subsequent wash solution can be decanted 'ed in a more satisfactory manner. lltis important, moreover, that the strength et the aforesaid barium sulphide solution should be between 'the ranges of 12% and 20% of barium sulphide content and also that the strength of the aforesaid sodium sulphate solution should'be between the ranges of 20% to 30% sodium sul hate content. i l

n arations from the aforesaid limits, either oilthe strength or the temperatures of the solutions employed, will result in the pro duction or al coarse precipitate ot barium sulphatewhich settles much slower and is accordingly less easily washed or decanted The precipitate obtained from the toregoing reaction is washed with water free trom iron or added orei salts, prelerabl waterwhich has been agitated with 4a ama l amount ot barium carbonate sucient to re move `any iron and. like impurities therein f and then 'dltered, as n? ordinary surface orwell wateris used the precipitated barium sulphate will 'be distinctly colored9 due to the formation or iron sulphide by interaction between`the salts `in the vwater' and rtf sodium sulphides et the top liquor. lln order to maintain at the maximum the advantages resulting from the tore oing treatment, itis also highly desirable t at the wash water ing con;

ica

slightest trace ot alkalinity) precipitated barium sulphate, or blaiic hire ol pure white color whose ultimateqparticles underl the microscope appear spherical in shape and amorphousratherthan cystalline in physiy 4 i t i 1,457,935

invention, various modications, within the 5 cal character and measure from "two to three micromillimeters" indiameter. 4

Withouteparting from the spirit of my scope of the appended claims, may be made in the within procedure. I

e c Having thus described my invention,- what I claim and desire to secure by Letters Patent is:y

1. The method of making preci itated barium sulphate which consists in e ectingA .double decomposition between a barium vsulphide solution containingvfrom 12% to 20% ',of barium sulphide anda sodium` sulphate solution vcontainin from 20% to 30%v of sodium sulphate, w ile maintaining the tem-V perature of -the mixture during the cipitation between 50 C. and 100 C. separating the resultant precipitate and washing the same with relatively hot water ofv a temrature of at least 60 C. and free from l iron andv deleterious salts. r

2'. the method of making precipitated barium "sulphate,the` step which consists in effecting- ,a reaction between a solution of barium sulphide containing from 12% to 20% ofbarium sulphide' and a solution of sodium sul hate containing from` 20% to '30%ofsod1um sul hate.`

g the metho of making precipitated phate solution containing from 20% to 30% of sodium sulphate, while maintainingthe temperature of the mixture during the p re'- cipitationbetween 60 C., and 75 C. separating the resultant precipitate and washing the same with relatively hot water of ,a temperature, of at least 60 C. and free from' iron and deleterious salts.

5. In the method of making precipitated barium sulphate, the, steps which consist in' eiecti'ng double decomposition between solutions of barium `sulphide and sodium sul- Y phate, while maintaining thetemperature of the mixture' during the decomposition reaction between 60 C. and 75 Ci.'-

Signed at Charleston, in the county of Kanawha and State of West Virginia,this

i 23rd'day of September, 1921.

JS B. PIERCE, nf.l

4o 20% of barium sulphide and a sodium sul- 

